Thermostatically-actuated electric control



June 10, 1930. w. w. WILLIAMS THERMOSTTICALLY ACTUATEP ELECTRIC QONTROLlNYEnTmR WALT E R W WILLIAMS EY'aa /w M Q A: TY

Filed Aug. 3, 1925 Patented June 10, 1930 UNITED STATES- PATENT OFFICEWALTER W. WILLIAMS, 0] BLOOMINGTON, ILLINOIS, ASSIGNOR TO WILLIAMSOIL-Or MATIG HEATING CORPORATION, OF BLOOMINGTON, ILLINOIS, ACORPORATION OF ILLINOIS THEBMOSTATICALLY-ACTUATED ELECTRIC CONTROLApplication flled August 8, 1925. Serial No. 47,700.

This invention relates to improvements in electric controls and moreparticularly to a device of this character which is actuatedthermostatically.

Devices of this character are used to great advantage in connection withdomestic heaters or furnaces in which an electric current is employed tooperate a motor to open and close dampers or for the purpose of operating a liquid fuel burner in connection with the furnace. It has beencustomary to apply devices of this character which are subjected to thetemperature of the gas within the stack leading from the furnace andthis type of control has received the commercial designation of stackcontrol. Such devices have a portion extending within the stackcontaining thermostatic elements which will expand upon the increase ofheat when the fire within the furnace is burning and contract when thefire goes out. The expansion and contraction of these elements aretransmitted to a mechanism for closing and breaking the circuit foroperating the motor.

It is an object of this invention to provide a device of this generalcharacter in which the actuating element is sensitive in its action anddue to its construction will contract very rapidly, when the source ofheat in the furnace has failed.

While a preferred form of this invention is illustrated upontheaccompanying sheet of drawing, yet, it is to be understood that minordetail changes may be made without de )arting from the scope thereof.

In the drawing Figure 1 is a view of an embodiment of this invention inside elevation with parts broken away and partly in section.

F igure 2 is a transverse sectional view taken upon the line 2-2 onFigure 1 looking in the ircction of the arrows.

Figure 1 illustrates this improved thermostatically actuated electriccontrol ada ted to be applied to the stack or pipe lea' ing from adomestic heating furnace for the purpose of controlli the operation ofan electric motor adapte to operate a domestic oil burner in connectionwith the furnace by closing or breaking the commercial electric circuitleading to the motor. The control is mounted upon a curved plate 1adapted to be secured to the stack or metal pipe of the furnace, whichis provided with a boss 2 extending on the exterior side adapted toreceive and secure thereto by a set screw a bushing 3 surrounding theactuating portions of the control which extend through the bushing andthrough a similar shaped orifice in the stack or pipe.

he electric connections and operatin parts are mounted upon a circularmeta plate 4 having a central circular opening 5 and a depending sleeve6 adapted to receive the shouldered end of a tube 7 which extendsthrough the bushing 3 into the interior of the stack or pipe leadingfrom the furnace, which tube is similarly shouldered at the other end. Ametallic bushing 8 of similar dimension to the depending sleeve 6 andhavin a similar circular aperture passing themt irough surrounds theother or inner end of the shouldered tube 7. Another metallic tube 9surrounds the do )ending sleeve 6, shouldered tube 7 and mshing 8surrounding the inner end which tube 9 is terminated flush with theexterior of said bushing and is secured thereto and to the shoulderedtube preferably by a pin 10 passing through the exterior tube 9 bushing8 and interior tube 7. This outer tube is received snugly but is capableof movement within the bushin 3 secured to the attaching plate 1 andexten s under normal conditions flush with the adjacent side of thecircular plate 4 carryin the electric connections. The surface of thisplate 4 is recessed substantially one-half its thickness about the deending sleeve. The shouldered tube 7 and t 10 surroundin outer tube 9are constructed of metal of di erent coefficients of expansion, and areso arranged that u n the portion within the stack or pipe lea mg fromthe furnace being subjected to heat in an increased degree, the outersurrounding tube 9 will expand longitudinally and travel over thedepending sleeve 6.extending into the recessed .portion of the undersidecircular plate 4. As there is an openin 5 in the center of this plate,which is pre erably of the same size as the inner diameter of theshouldered tube 7 and a similar opening in the bushing 8 at the otherend of the shouldered tube, when the source of heat within the furnacefails the upward natural draft from the furnace through the stack willdraw atmospheric air through these openings and as the heat decreasesfrom the furnace the cool air drawn through these elements of thecontrol will impart an increased rate of contraction to the slidingouter sleeve to its original or normal position.

The operating mechanism for making and breaking the electric circuitincludes a post 11 secured to the outside of the outer surrounding tube9 which extends'there beyond and enters through a cut-away portion 12therefor in the adjacent circular plate 4 so that as the tube expandsthis post will be eX- tended beyond the upper surface of the circularplate and as the tube contracts the post will be Withdrawn. Two bindingposts 13 and 14 are arranged on the upper surface of the circular plate4 for receiving and securing the terminals of the leads 15 from thecommercial source of the electricity to the motor. One terminal 13 isconnected by a lead 16 to a fixed contact point 17 secured to andinsulated from the same surface of the circular plate 4. The otherterminal is connected by a lead 18 to a binding post of a movablecontact 19 carried upon a plate 20 pivoted at one end to a bracket 21extending upward from the same surface of the circular plate 4. Thearrangement of the contacts 17 and 19 being such that upon movement ofthe pivoted plate the circuit will be closed or broken. The pivotedplate 20 is held by a spring 22 secured to the bracket to close thecircuit between the contacts and is provided with an adjustable member23 depending from the under side thereof, adapted to be engaged by theend of the post 11 carried on the outer sliding tube 9, which member isso adjusted that when the tube is in the normal or contracted positionthe circuit will be closed and upon expanding, when subjected to anincreased heat within the stack or pipe leading from the furnace, thepost entering above the upper surface of the circular plate will liftthe depending member 23- and rotate the contact carrying plate 20 aboutits pivot to break the circuit. It is preferable to provide a bracket 24attached to the u per surface of the circular plate 4 by the xed contactsecuring means which bracket extends above the moveable contact bindingpost and is provided with an adjustable insulated stop.

25 adapted to prevent abnormal movement of the moveable contact. 4

It is preferable to mount the moveable contact 9 upon a shaft 29 whichpasses through an aperture in the pivoted plate 20 which shaft isprovided with a fixed collar 30 upon the under-side of the plate 20 toprevent further upward movement through the plate. This shaft whichmounts the binding post 31 at its upper end is surrounded by a lavainsulating block 32 threaded into the plate 20 and of less height thanthe distance between the binding post and the upper surface of thepivoted plate when it is in contact with the shoulder on the contactcarrying shaft. It is preferable to provide opposite sides of the lavablock with fiat longitudinal surfaces and also a plate of spring metalsecured to the binding post 31 with depending side portions 33 bent backupon themselves to frictionally engage the opposite flat surface of thelava block with a sliding contact. By this construction as the post 11lifts the pivoted plate 20 upon expansion of the outer tube 9, thecontacts 1}) and 17 are separated and the circuit broken. As the heat inthe furnace increases the tube 19 will continue to expand and the post11 will continue to lift the contact carrying end of the pivoted plate20. The initial movement of the plate 20 has carried the moveablecontact binding post into an engagement of the stop 25; further movementwill cause the plate 20 to slide over the contact carrying shaft 29carrying the lava block 32 with it until the top of the lava blockengages the underside of the binding post 31. Upon contraction of thetube 9 and Withdrawal of the post 11, the spring 22 will cause the freeend of the pivoted plate 20 to descend. The lava block 32 being attached to the plate and having frictional contact with the dependingside portions 33 of the metal plate 31 secured to the upper end of theshaft 29 of the moveable contact will cause this shaft to descend withthe movement of the plate 20 until the contacts engage, the plate 20descending over the shaft thereafter until the underside is engaged bythe collar 30. By this contraction it is seen that the frictionalcontact between the lava block and depending arms of the plate 31carried on the upper end of the moveable contact shaft will cause thecontact to move with the plate 20 upon an initial upward movement,breaking the circuit, and likewise will cause the contact carrying shaftto move downward with the plate 20 simultaneously with the withdrawal ofthe post 11 upon the contraction of the tube 9. By the proper adjustmentof the member 23 carried on plate 20 which is engaged upon expansion bythe post 11 and by the proper adjustment of the stop 25 adapted to beengaged by the upper end of the moveable contact carrying shaft 29, thecircuit may be broken at a predetermined temperature of the interior ofthe stack, and moving of the contact carrying post away from the fixedcontact may also be limited at a higher predetermined temperature, sothat upon a denism 1t 1s preferable to provide a cylindrical tion; alsowill cause the contact carrying post to descend simultaneously with theplate and engage the fixed contact post closing the circuit at oncewithout delaying until the temperature has decreased below thepredetermined amount to which the stop has been adjusted. v

To protect the switch parts and mechahousing 26 about them secured tothe circumference of the circular plate 4,which housing is provided withapertures 27 around its sides and top for the admission of atmosphericair and for the leads 15 of the electric circuit to, pass therethrough.

sired.

While the leads 16 and 18 may be of commercial insulated ,wire. it ispreferred to mount one or more insulated beads 28 on each lead toprevent the wire from contacting with any of the'metal parts ofmechanism.

Reference has. been made to the articu-' lar construction providin whatmight be called an air duct throng the electric operating andthermostatic actuating means, also that the shouldered tube 7 and theouter surroundin tube 9 are constructed of materials having differentcoefficients of'expansion. It is preferable to form the shouldered tube7 of iron and the outer surrounding tube 9 of brass, so that the brasstube fire in the furnace goes out.

\Vhile this control has been described as having the thermostaticelements entering into the stack leadingfrom the furnace of a domesticheater, it is obvious that. the control may be installed whereverdesired, so long as the thermostatic elements are subjected to thevariations in temperature within the furnace roper and may be applied tothe furnace 001', for example, if so de- What I claim is 1. A stackcontrol device for electrically operated heating furnaces comprising anelectric circuit making and breaking mechperature therein, saidmechanism comprisanism mounted upon the exterior of the. stack havingthermostatigactuating members for said mechanism entering the'interior0f the stack and subjected to the variations of teming a fixed contact,and a moveable contact a normally closing the circuit, said,moveablecontact carried on a plate having adjustable means adapted to beengagedupon the expansion of a thermostatic member and at a predeterminedtemperature within the stack be moved to break the circuit, saidmoveable contact having a slideable engagement with said plate andadjustable means to limit the movement of said contact with said plateaway from said fixed contact and allowing further movement of the platein that direction, and means causing the contact to always move with thepl'ate. inthe direction of the fixed contact. v

2. A stack control device for electrically operated heating furnaces,comprising an electric circuit making and breaking mechanism mountedupon the exterior of the stack having thermostatic actuating membersforsaid mechanism entering the interiorof the stack and subjectedto thevariations of temperature therein, said mechanism comprising a fixedcontact, and a spring pressed pivoted plate adapted to be engaged by oneof the thermostatic elements and caused to rotate about its pivot uponexpansion and contraction of said element, a contact carried on a shaftpassing through the free end of said plate having a slideable andfrictional engagement with said plate, a stop over said shaft limitingthe movement of'the shaft in that direction, said frictional engagementcausing the contact to move simulshaft in relation to said plate.

WALTER W. WILLIAMS.

